1. Field of the Invention
The present invention relates to a thin film magnetic recording head used for, for example, a floating magnetic head. More particularly, the present invention relates to a thin film magnetic head intended to decrease inductance to be made adaptable to higher recording frequencies, and a method of manufacturing the same.
2. Description of the Related Art
FIG. 18 is a partial front view showing the structure of a conventional thin film magnetic head (inductive head). FIG. 19 is a partial sectional view of the thin film magnetic head shown in FIG. 18 taken along line XIX—XIX, as viewed from the direction of arrows.
In FIGS. 18 and 19, bottom core layer 1 is made of a magnetic material such as permalloy or the like. Insulating layer 9 is formed on the bottom core layer 1.
The insulating layer 9 has a trench 9a which is formed in the height direction (the Y direction shown in FIG. 18) from the air bearing surface (referred to as “ABS” hereinafter) facing a recording medium to have an inner width dimension equal to the track width Tw.
Also, a bottom pole layer 3 magnetically connected to the bottom core layer 1, a gap layer 4 and a top pole layer 5 magnetically connected to a top core layer 6 are formed in the trench 9a by plating in turn from the bottom.
As shown in FIG. 19, a coil layer 7 patterned in a spiral shape is provided on the portion of the insulating layer 9, which is located at the back of the trench 9a formed in the insulating layer 9 in the height direction (the Y direction shown in FIG. 19).
The coil layer 7 is covered with an organic insulating layer 8 of resist or the like. The top core layer 6 is formed on the organic insulating layer 8. The front end 6a of the top core layer 6 is magnetically connected to the top pole layer 5. The base end 6b is magnetically connected to the bottom core layer 1.
In the inductive head shown in FIGS. 18 and 19, when a recording current is supplied to the coil layer 7, a recording magnetic field is induced in each of the top and bottom core layers 1 and 6. A magnetic signal is recorded on a recording medium such as a hard disk by a leakage magnetic field between the bottom pole layer 3 and the top pole layer 5 magnetically connected to the bottom core layer 1 and the top core layer 6, respectively.
In the inductive head shown in FIGS. 18 and 19, the bottom pole layer 3, the gap layer 4 and the top pole layer 5 are locally formed with the track width Tw near the ABS (the surface facing the recording medium). This type of inductive head is adaptable to narrower tracks.
The method of manufacturing the inductive head shown in FIGS. 18 and 19 is described below. First, the insulating layer 9 is formed on the bottom core layer 1. The trench 9a having the track width Tw is formed in the insulating layer 9 with a predetermined length from the ABS in the height direction.
Next, the bottom pole layer 3, the gap layer 4 and the top pole layer 5 are continuously formed by plating in the trench 9a. The coil layer 7 is patterned on the portion of the insulating layer 9, which is located at the back of the trench 9a formed in the insulating layer 9.
Furthermore, the coil layer 7 is covered with the organic insulating layer 8. The top core layer 6 is formed by frame plating to extend from the top pole layer 5 to the organic insulating layer 8 to complete the inductive head shown in FIGS. 18 and 19.
It is necessary to decrease the inductance of the inductive head with track narrowing accompanying increases in recording density and recording frequency in future.
In order to decrease the inductance, the magnetic path formed from the bottom core layer 1 to the top core layer 6 must be shortened. Thus, the width dimension T1 of the coil layer 7 formed between the front end 6a and the base end 6b of the top core layer 6 must be decreased. By decreasing the width dimension T1 of the coil layer 7, the length of the top core layer 6 can be shortened to realize a short magnetic path.
A possible method of decreasing the width dimension T1 of the coil layer 7 without changing the number of the turns of the coil layer 7 is one in which the coil layer 7 is formed in a laminated structure comprising two layers.
However, in the structure of the thin film magnetic head shown in FIGS. 18 and 19, even when the coil layer 7 has a simple two-layer laminated structure, the magnetic path cannot be shortened so that it is made adaptable to higher recording frequency in future, thereby causing difficulties in appropriately decreasing inductance.
This is because the coil layer 7 is formed on the thick insulating layer 9. As shown in FIG. 18, the insulating layer 9 has a thickness H5 which is more than the total thickness H6 of the bottom pole layer 3, the gap layer 4 and the top pole layer 5. Therefore, assuming that the surface of the top pole layer 5 is a reference plane, the coil layer 7 is formed on the insulating layer 9 nearer the top core layer 6 than the reference plane, as shown in FIG. 19.
Therefore, with the coil layer 7 having a two-layer laminated structure, the width dimension T1 of the coil layer 7 can be decreased, but the height from the top of the bottom core layer 1 to the top of the insulating layer 8 formed to cover the coil layer 7 is substantially increased. As a result, the magnetic path cannot be much shortened, and the inductance cannot be appropriately decreased.
In the inductive head having the structure shown in FIG. 19, with the coil layer 7 having two-layer laminated structure, the thickness dimension H1 of the organic insulating layer 8 formed to cover the coil layer 7 is increased. Thus the organic insulating layer 8 significantly rises from the surface of the top pole layer 5 as the reference plane.
Therefore, the top core layer 6 cannot be easily formed by frame plating to extend from the top pole layer 5 to the organic insulating layer 8, thereby causing the problem of making it impossible to form the top core layer 6, particularly the portion near the front end 6a thereof, in a predetermined shape.